The present invention relates to a device containing a solar cell panel and a storage battery integrally, which is preferable as an electronic power supply or source for facilities in remote places, mobile station and so on.
Solar cell panels are widely used in view of their energy efficiency and non-maintenance. A maintenance-free power source is particularly useful in remote places.
However, not only a silicone solar cell panel (such as a single crystal silicone solar cell panel, a polycrystal silicone solar cell panel, or an amorphous silicone solar cell panel) but also a thin film solar cell panel (such as a gallium arsenide thin film solar cell panel) can generate electricity only when it receives light such as solar light and so on, and it cannot generate any power at nighttime and under cloudy or rainy conditions even if it is daytime, power generation is remarkably reduced.
Consequently, in a case where a conventional power supply (or system power supply) is provided through distribution lines or cables, a solar cell panel and the conventional power supply are used in parallel, and when an output voltage from the solar cell panel falls below a predetermined level, the power from the conventional power supply is provided to a load. Obviously, however, this method requires power distribution means (or power distribution cables) and thus it is impossible to be employed in a case where there is no distribution means of a conventional power supply. Further, a conventional power supply usually provides an AC voltage, while a solar cell panel provides a DC voltage. Therefore, a converter and/or an inverter is required to convert the AC or DC voltage output from the conventional power supply or solar cell panel to an appropriate current, or a DC or AC voltage to be applied to a load, even if the load is an AC load or a DC load.
Furthermore, in a case where there is a great discrepancy between a time period during which a solar cell panel can generate and charge electrical power and a time period during which a load power is consumed, there is little advantage in using a solar cell panel in order to supplement the capability of power generation. For example, when a load is an air cooling system which is usually used in summer time, power generation in a solar battery substantially coincides with power consumption of the air cooling system, and when a load is an air heating system which is usually used at night in winter or a TV receiver which is usually turn-on at night, power generation in a solar cell panel may well not coincide with power consumption of the air heating system or TV. In the former case, there is a great advantage in employing the solar cell panel for electricity requirements, while in the latter case, there is little advantage therein.
Accordingly, if there is no main power supply or conventional power supply is available and power is consumed during period when no light reaches the solar cell panel, a system is employed in which power generated by the solar cell panel is charged to a storage battery.
In this case, however, a place for positioning the storage battery thereat is needed, and when power storage is required on a large scale, a chamber for accommodating the storage battery is needed. In addition, since the solar cell panel is produced separately from the storage battery, it is necessary to properly match the voltages of the solar cell panel and the storage battery, otherwise poor performance results. That is, charging to the storage battery is made impossible, or an operating point of the solar cell panel greatly deviates from the maximum performance point. Therefore, solar cell panel manufacturers, storage battery manufacturers or third party equipment fabricators have to adjust the output voltage of the solar cell panel or storage battery to coincide with the other.
Although a polymer battery, which is a kind of a solar cell panel having a power charging function, has been fabricated, it is still at laboratory level. Neither there has been developed nor put to practical use such a type of solar cell panel having the same power generation capability as that of a silicone solar cell panel.